Elastic wave device

Abstract

An elastic wave device includes a piezoelectric substrate including first and second primary surfaces opposing one another, a via electrode extending through the piezoelectric substrate, and a wiring electrode on the first primary surface of the piezoelectric substrate. The via electrode is connected at one end to the wiring electrode, and the via electrode includes a locking section at the one end, on the wiring electrode side. The locking section extends on the first primary surface of the piezoelectric substrate.

What is claimed is: 
     
       1. An elastic wave device comprising:
 a piezoelectric body including opposing first and second primary surfaces; 
 a via electrode extending through the piezoelectric body; and 
 a wiring electrode disposed on the first primary surface of the piezoelectric body; wherein 
 the via electrode is connected at one end to the wiring electrode; 
 the via electrode includes a locking section at the one end, on a wiring electrode side, the locking section extending on the first primary surface of the piezoelectric body; 
 the wiring electrode is a multilayer body including a plurality of layers; and 
 the plurality of layers include a layer more resistant to wet etching than an outermost layer of the plurality of layers on a piezoelectric body side of the wiring electrode. 
 
     
     
       2. The elastic wave device according to  claim 1 , wherein
 the piezoelectric body includes a through hole; 
 the via electrode includes a through section as a portion positioned inside the through hole; and 
 the locking section of the via electrode has a cross-sectional area larger than a cross-sectional area of the through section at an end on the first primary surface side. 
 
     
     
       3. The elastic wave device according to  claim 1 , wherein a surface of the locking section in contact with the wiring electrode is a roughened surface. 
     
     
       4. The elastic wave device according to  claim 1 , wherein at least one excitation electrode is provided on the first primary surface of the piezoelectric body. 
     
     
       5. The elastic wave device according to  claim 1 , wherein the piezoelectric body with the wiring electrode thereon is a lid, and the elastic wave device further includes an extra piezoelectric body positioned opposite to the lid and provided with at least one excitation electrode. 
     
     
       6. The elastic wave device according to  claim 4 , wherein the at least one excitation electrode includes at least one interdigital transducer electrode. 
     
     
       7. The elastic wave device according to  claim 1 , wherein the piezoelectric body is a piezoelectric substrate made of one of lithium tantalate, lithium niobate, potassium niobate, quartz, langasite, ZnO, PZT, and lithium tetraborate. 
     
     
       8. The elastic wave device according to  claim 6 , wherein the at least one IDT electrode is a single layer or a multilayer body. 
     
     
       9. The elastic wave device according to  claim 1 , further comprising a support on the first primary surface of the piezoelectric body. 
     
     
       10. The elastic wave device according to  claim 9 , wherein the support covers at least a portion of the wiring electrode. 
     
     
       11. The elastic wave device according to  claim 9 , wherein the support includes a cavity. 
     
     
       12. The elastic wave device according to  claim 11 , further comprising at least one interdigital transducer electrode in the cavity. 
     
     
       13. The elastic wave device according to  claim 9 , wherein the support is made of resin. 
     
     
       14. The elastic wave device according to  claim 11 , further comprising a cover that closes the cavity. 
     
     
       15. The elastic wave device according to  claim 1 , wherein the wiring electrode includes a hollow portion that extends to the first primary surface of the piezoelectric body. 
     
     
       16. The elastic wave device according to  claim 1 , wherein the piezoelectric body includes a through hole, and the wiring electrode includes a hollow that joins the through hole. 
     
     
       17. The elastic wave device according to  claim 2 , wherein the through section is a portion in which metal of the via electrode fills the through hole. 
     
     
       18. The elastic wave device according to  claim 16 , wherein the locking section is a portion in which a metal fills the hollow. 
     
     
       19. The elastic wave device according to  claim 16 , wherein the wiring electrode includes two electrode layers, and the hollow extends to at least one of the two electrode layers. 
     
     
       20. An elastic wave device comprising:
 a piezoelectric body including opposing first and second primary surfaces; 
 a via electrode extending through the piezoelectric body; and 
 a wiring electrode disposed on the first primary surface of the piezoelectric body; wherein 
 the via electrode is connected at one end to the wiring electrode; 
 the via electrode includes a locking section at the one end, on a wiring electrode side, the locking section extending on the first primary surface of the piezoelectric body; 
 the wiring electrode is a multilayer body including a plurality of layers; and 
 the plurality of layers include a layer made from Pt or Au that is more resistant to wet etching than an outermost layer of the plurality of layers on a piezoelectric body side of the wiring electrode.